The present invention relates to a system for controlling the amount of intake air of an engine for a motor vehicle having a fuel injection system.
The amount of injecting fuel in an electronic fuel injection system for a vehicle is controlled in accordance with the amount of intake air measured by an air flow meter and with the speed of an engine. During the coasting of the vehicle, a throttle valve of the engine is closed to idle the engine. Accordingly, the amount of intake air is small, thereby reducing injected fuel. In the coasting state, when an accelerator pedal is depressed in order to re-accelerate the vehicle, the amount of intake air increases rapidly to increase the torque of engine. Dotted lines of FIGS. 3b and 3c show examples of sudden increases of the engine torque, which are caused by an increase of opening degree of a throttle valve shown in FIG. 3a. Such a sudden increase of engine torque causes jerk of the vehicle, which shocks the driver of the vehicle.
In order to solve the above described problems, heretofore, devices for delaying the operation of throttle valve by elongating the stroke of the accelerator pedal or by shaping a throttle cam to a particular shape have been employed. However, it is difficult to increase the stroke of the accelerator pedal due to structural conditions. On the other hand, the configuration of the cam for providing an irregular speed operation of the throttle valve causes irregular load of the accelerator pedal, that is, the load is light in a small throttle open range and heavy in a wide throttle open range.